Single inlet centrifugal fan

ABSTRACT

The invention relates to single inlet centrifugal blowers or fans. The fan is of less axial length than the width of the housing. The rear closed end wall of the housing confronting the backwall of the fan is provided with an inwardly extending cylindrical surface of substantially the same diameter as the fan and terminating in close spatial relation to the backwall of the fan. The cylindrical surface may be formed integral with the closed housing wall, or as a separate piece attached to the housing wall, or as part of the motor mount. The cylindrical surface serves to direct secondary rotational airflow from the space or cavity between the fan backplate and the rear wall of the housing.

United States Patent Charles E. Bullock [72] Inventor North Syracuse, N.Y. i211 Appl No. 12,005 [22] Filed Feb. 17.1970 [45] Patented Nov. 9,1971

Assignee Carrier Corporation Syracuse. N.Y.

[541 SINGLE INLET CENTRIFUGAL FAN 3 Claims, 5 Drawing Figs.

[52] U.S. Cl 417/423. 416/178 [51] int. Cl.".' ..F04b 17/00, I F04d 17/08 [50] Field 01 Search 417/423; 416/178, 179. 180. 181, 182

[56] References Cited UNITED STATES PATENTS 1,163.543 12/1915 llg .4 417/423 Primary Examiner-Robert M Walker AImrneys-Harry G. Martin, Jr. and 1 Raymond Curtin ABSTRACT: The invention relates to single inlet centrifugal blowers or fans. The fan is ofless axial length than the width of the housing. The rear closed end wall of the housing confronting the backwall of the fan is provided with an inwardly extending cylindrical surfaceof substantially the same diameter as the fan and terminating in close spatial relation to the backwall ofthe fan. The cylindrical surface may be formed integral with the closed housing wall, or as a separate piece attached to the housing wall, or as part of the motor mount. The cylindrical surface serves to direct secondary rotational airflow from the space or cavity between the fan backplate and the rear wall ofthe housing PATENTEDunv 9 nan SHEET 1 [IF 2 FIG! FIG. 3

6 20 FIG. 5 INVENTOR.

CHARLES E. BULLOCK BY @WVM ATTORNEY PATENTEUNUV 91911 SHEEI 2 BF 2 FIG. 6

FIG.

INVENTOR. CHARLES E. BULLOCK FIG. 7

ATTORNEY snvcu: INLET CENTRIFUGAL FAN BACKGROUND OF THE INVENTION There are known advantages in employing a housing of substantially greater length than the axial length of the centrifugal fan. However, with that arrangement in single inlet fans, secondary rotational airflow patterns can be setup in the cavity or space between the backplate of the fan and the rear closed wall of the housing. Such patterns dissipate significant amounts of turbulent energy, reducing the efficiency of the fan.

SUMMARY OF THE INVENTION This invention is directed to an improved single inlet centrifugal fan structure wherein the fan, having an axial length less than the width of the housing, is mounted substantially midway between the inlet end and the rear closed end of the housing. A cylindrical surface extends inwardly from the rear wall of the housing and is of approximately the same diameter as the fan and terminates in close proximity thereto. The cylindrical surface serves as a barrier to prevent secondary rotational air moving in the space between the backplate of the fan and the rear housing wall. The cylindrical surface may be formed integral with the rear housing wall or provided by a separate piece affixed to the housing wall. In either arrangement, the centrifugal surface is preferably incorporated in the mounting structure for the fan motor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevational view of a centrifugal fan structure embodying my invention;

FIG. 2 is an end elevational view looking to the left of FIG.

FIG. 3 is a view taken on line 3-3 of FIG. 2;

FIG. 4 is a view taken on line 4-4 of FIG. 3 with the fan removed;

FIG. 5 is a view similar to FIG. 3 showing a modified motor mount structure;

FIG. 6 is a view taken on line 6-6 of FIG. 5; and

FIG. 7 is a view similar to FIG. 3 showing a modified form of the motor mount structure shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The fan housing illustrated in the drawings consists of end members 10, 11 and a scroll member 12 extending between the end members and affixed thereto. The end member is formed with an opening in which an inlet bell 13 is mounted. The end members 10, 11 are D-shaped in general form having a flat planar edge surface formed by an outwardly bent flange 15. The side edges of the end members extend normal from the linear edge surface as indicated by the portions 17, these portions merging with a circular edge portion 18. The edge portions l7, 18 are formed with inwardly bent flanges 20.

The scroll member 12 is formed of relatively thin sheet material such as sheet metal or plastic and is formed at one end with an outwardly bent flange 23 which is positioned on outwardly bent portions 25 of the flange 20. These outwardly bent portions 25 of the flange 20 are offset downwardly slightly from the plane of the linear edge flange (see FIG. I). The ends of the scroll 12 are positioned within the flanges of the end members and are affixed thereto by fasteners 27.

The opposite end of the scroll 12 is formed with a plate 30 of substantial length. The joinder of the scroll with the inner end of the plate 20 forms the cutoff 31 (see FIGS. 4 and 6). The outer end of the plate 30 also overlaps the flanges at the opposite sides of the end members. The end members 10, 11 are each formed with an embossment extending inwardly from the inner surface of the end member and including an arcuate portion 33 and a linear portion 34 positioned immediately below the linear edge surface of the end members. These embossments serve to position and locate the cutoff end portion of the scroll.

Referring to FIGS. 3, 5, and 7, it will be seen that the end members 10, 11 are spaced apart a distance considerably greater than the axial length of the centrifugal fan 40. The inlet bell 13 extends inwardly a substantial distance from the end member 10. A cylindrical surface 41 extends inwardly from the rear or closed wall 11 and tenninates in close proximity to the inner end of the fan 40, and is substantially the same diameter as the fan. This surface 41 serves as a barrier to prevent secondary rotational air moving in the space between the end wall 11 and the inner end of the fan.

Referring to FIGS. 1, 2, and 3, the cylindrical surface 41 is fonned integral with the end wall 1 l. The end wall l] is drawn to provide an inwardly extending circular flange 45 merging with a radially inwardly extending portion 46 apertured at its center for attachment to one end of the fan driving motor 47.

As shown in FIG. 3, the portion 46 is formed with an inner cylindrical flange 48 dimensioned to engage a metal ring 49 fixed to the motor-bearing boss 50 by a resilient sleeve 51. With the motor mounted to the end wall in this manner, an outboard motor support is affixed to the wall 11. This outboard motor support is formed complemental to the portions 45, 46, 48 of the structure formed integral with the end wall. This outboard support 53 is attached to the end wall as by fasteners 55, flange portion 58 engaging the resilient mounting structure carried by the motor-bearing boss 59 at the opposite end of the motor.

The fan 40 is formed with a conical-shaped backwall 60 fixed to the motor shaft 61. The portion 46 and the complemental portion of the outboard support 53 and may be formed with venting holes 63.

The arrangement shown in FIG. 7 is similar to that described in connection with FIGS. 1-3. However, in FIG. 7 the end wall 11 is drawn outwardly to provide an integral motor mount for engagement with the outer motor-bearing boss 59. An inboard motor support 65 embodying structural form similar to that of the outboard support 53 is attached to the inner surface of the end wall 11 as by the fasteners 55, the circular flange portion 67 of this inboard support forming the cylindrical barrier surface 41.

Referring to FIG. 5, the end wall 11 is drawn to provide a circular flange 70 extending inwardly and merging with an outwardly extending conical portion 71 terminating in a central discoidal portion 72 to which the fan motor 47 is affixed as by fasteners 73. In this arrangement, the flange 70 provides the cylindrical surface 41 providing the barrier between the inner end of the fan and the closed wall 11 of the housing.

In structures described, the cylindrical surface 41 not only serves as a barrier to prevent secondary rotational airflow patterns between the backwall of the fan and the closed wall of the housing, but also the motor is not positioned in the primary airstream and thus does not degrade the aerodynamic performance of the fan as is the case in conventional fan structures. The formation of the cylindrical barrier surface incorporated in the motor mounts greatly increases the stiffness and rigidity of the mounts and makes the unit less sensitive to fan wheel or motor imbalance.

I claim:

I. A centrifugal single inlet fan structure comprising a housing having a rear closed end wall and an inlet end wall formed with an inlet opening, a fan joumaled for rotation in said housing intermediate said walls, said walls being spaced apart a distance greater than the axial length of said fan, a motor operatively connected to said fan for effecting rotation thereof, said rear wall being formed with a first integral radially inwardly extending central portion offset axially from the plane of said wall, a motor support member of circular form fixed at its periphery to said rear wall and being formed with a radially inwardly extending central portion formed complemental to said central first portion and being spaced axially from said first portion, said central portions being formed with aligned apertures, said motor being mounted between said portions, the ends of said motor being fixedly mounted in said apertures.

2. A centrifugal fan structure as set forth in claim 1 wherein said motor support member is attaches to the outer surface of said rear wall.

3. A centrifugal fan structure as set forth in claim 1 wherein said motor support member is attached to the inner surface of 5 said rear wall.

i i i ll i 

1. A centrifugal single inlet fan structure comprising a housing having a rear closed end wall and an inlet end wall formed with an inlet opening, a fan journaled for rotation in said housing intermediate said walls, said walls being spaced apart a distance greater than the axial length of said fan, a motor operatively connected to said fan for effecting rotation thereof, said rear wall being formed with a first integral radially inwardly extending central portion offset axially from the plane of said wall, a motor support member of circular form fixed at its periphery to said rear wall and being formed with a radially inwardly extending central portion formed complemental to said central first portion and being spaced axially from said first portion, said central portions being formed with aligned apertures, said motor being mounted between said portions, the ends of said motor being fixedly mounted in said apertures.
 2. A centrifugal fan structure as set forth in claim 1 wherein said motor support member is attached to the outer surface of said rear wall.
 3. A centrifugal fan structure as set forth in claim 1 wherein said motor support member is attached to the inner surface of said rear wall. 